The invention relates to improvements to implantable vascular access devices.
Implantable vascular accesses are used mainly in cases where repeated operations involving puncturing (sampling), dialysis (treatment), chemotherapy treatment, perfusion feeding, or other operations of this type, have to be repeated periodically a great many times over a long period.
The known devices essentially comprise a chamber in the form of a flat capsule lodged under the skin, communicating with a vein, the chamber being sealed on the skin side by a membrane called a "septum" made of elastomer or silicon and which is possible to perforate a great number of times without impairing the leakproofness of the system. So as not to damage the septum, it is essential that the puncturing be carried out with the aid of special needles with a bevelled head, of small diameter, not exceeding an external diameter of 0.7 mm.
This limitation on the diameter of the needles which can be used constitutes a major disadvantage, which means that such vascular accesses cannot be used for the perfusion of high-viscosity solutions, particularly for feeding or various chemotherapy treatments, nor for the rapid perfusion of large volumes, as in the case of blood transfusions, nor for taking from the body samples of blood for analysis or purification, in particular in a dialysis treatment.
Under these conditions, for all of the interventions of the type mentioned above, and many others, it is necessary to have recourse to external catheters which have serious disadvantages, especially with respect to the risk of infection which their use involves, or which are at the origin of accidents due to voluntary or accidental tearing-out of the catheter, these devices moreover being very uncomfortable for the patient.
The invention relates to improvements to implantable vascular access devices, permitting the use of such accesses even in cases where high flow rates are used, both for sampling and for feeding, or in cases where solutions of high viscosity are used, making it necessary to employ access channels of considerable diameter.